1. Technical Field
The present invention relates to a travel control apparatus for a vehicle provided with a self-driving function which enables a vehicle to automatically turn to the right or turn to the left at an intersection along a target course, on a basis of travel environment information and travel information of the vehicle.
2. Related Art
In the related art, with regard to turn of a vehicle at an intersection, various driving assistance techniques have been developed and practically utilized. For instance, Japanese Unexamined Patent Application Publication No. 2005-189983 discloses a technique as follows. A road surface friction coefficient (road surface μ) of a road surface on which a vehicle travels is estimated, and a time required when the vehicle travels a right turn completion distance required for completing right turn after starting the right turn at an acceleration corresponding to the road surface μ is calculated as a right turn completion time. On the basis of the right turn completion time, a possibility of collision between the vehicle and other vehicles is determined so as to perform alarm control and acceleration/deceleration control of the vehicle.
Incidentally, in recent years, a self-driving technique has been developed and practically utilized. This self-driving has the following possibility. When the vehicle makes a turn at the intersection while crossing ahead of an oncoming vehicle, for instance, in a case where the turn is automatically controlled in response to a relative distance between an oncoming vehicle and the vehicle, and in a case where a road surface condition shows a low μ road, the vehicle's tire may slip during the turn, and the targeted acceleration cannot be obtained. Therefore, in a case where the oncoming vehicle is present, the vehicle may come into contact with the oncoming vehicle. In addition, if the vehicle has an in-vehicle traction control mounted for preventing tire slippage by decreasing a drive torque in response to a tire slippage state, in a case where the road surface condition shows the low μ road, the drive torque is frequently decreased due to an operation of the traction control. The acceleration becomes discontinuous during the right turn control, thereby vibrating the vehicle. Consequently, there is a possibility that occupants of the vehicle may feel anxiety or discomfort.